The present invention relates to a gear box comprising elliptical gearing according to the Cardan circle system with a spur wheel rollable along an internally toothed annular gear.
Such gears serve to translate the constant angular speed of a rotating driving or input shaft into a periodically variable angular speed of a driven or output shaft.
For this, a Cardan crank or elliptical spur wheels or an anti-parallel crank may be employed. However, all these gearings have the property of generating a constantly equal period in respect of the angular speed, i.e. the same ellipse is repeatedly transversed. Although the shape of the ellipse may be altered so that one obtains other speed relationships, however for example in the case of a Cardan circle pair, the point on the rolling circle spur wheel describing the ellipse must be altered, i.e. redisposed for this purpose in that this point is moved radially outwardly or inwardly. For this, the gearing must be stopped and manually reset. This resetting can thus be undertaken only at standstill and may be difficult to accomplish.